Development of the 3-D Measurement System of Lightning Transient Magnetic Field Based on Tunneling Magnetoresistive Effect

In order to accurately measure the three-dimensional transient magnetic field component generated by the discharge current of lightning struke high-speed railway catenary, this paper firstly establishes a simple calculation model of lightning struck high-speed railway catenary, and studies the temporal and spatial distribution characteristics of lightning stroke transient magnetic field in bridge section through calculation. And the design requirements and performance parameters of the measurement system are proposed according to the magnetic field characteristics. Then based on the Tunneling Magnetoresistive Effect (TMR), a three-dimensional measurement system of lightning transient magnetic field is designed and manufactured. In this study, three tunneling magnetoresistive sensors are used as the sensing probe, whose pairwise orthogonal design makes the measurement probe volume smaller and easier to measure. What's more, a signal processing circuit is designed to regulate the output signal, which is then collected through the signal collection module. Finally, the test scheme is designed to calibrate the time domain and verify the performance of the measuring system. The test results show that the measurement system is small in size, high in integration, fast in response to lightning transient magnetic field with the measurement dynamic range reaching $\pm\mathbf{5000A}/\mathbf{m}$ , which can basically meet the measurement requirements of transient magnetic field component in any direction generated by the discharge current of the lightning struck high-speed railway catenary.